Rotary grinders are used extensively in industry. More specifically angle type grinders/sanders of the grinding disc or pad type, are used for grinding fiberglass, wood, steel, removing asbestos and body filler in automobile shops, and for making boats and similar products. In use this grinder creates large quantities of dust that are both a fire hazard and a health hazard. Wood dust, for example, can be very explosive over a wide range of concentrations and is a known fire hazard. Hot metal grindings are particularly dangerous as fire starters. Both wood dust and metal filings as well as asbestos particles, fiberglass and body filler particles create known health hazards to users of the grinders and to others in the immediate environment.
Further, grinder discs and pads often rotate in the order of 7,000 revolutions per minute (RPM). Grinding pads that use a sponge type backing material create a hazard where parts or particles from the backing material break off and are shot from the rotating disc tangently at a high rate of speed. In this regard, it is often necessary to use a rotary grinder to grind into corners or against surfaces that have side edges, that can cause particles of the foam backing material to break off from the high speed rotating disc and hit the operator or other persons or equipment in the immediate area.
While there are prior art shrouds that go over the rotating disc, they are generally characterized by providing an enclosure that has openings around the shroud that allows material and dust to be shot out from the rotating disc or pad; or that have end portions open through which the dust and particles can escape or be distributed from rotating discs at a high speed; or comprise complex mechanism that contemplate spinning the shroud with rotating disc; all of which cause problems in use.
So it is desirable to provide a simple hood attachment that completely encloses the rotating grinding disc or pad and protects the surrounding area from particles being shot out or rotatably distributed from the rotating grinding disc. It is further desirable to have a means of collecting the rotating particles and the contaminated air flow generated by the rotating disc or pad through a tangently oriented exhaust opening through the enclosing hood or shroud. It is further desirable to have a shroud or hood with an enclosing skirt that floats against and with the work surface, and which skirt is capable of flexible resilient vertical movement to follow the surface of the work being ground by the grinding disc. It is further desirable to have a means for providing air to the chamber enclosed by the hood, to resupply the air flow out the exhaust port.